The present invention relates generally to producing forces in haptic feedback interface devices, and more particularly to the output and control of vibrations and similar force sensations from actuators in a haptic feedback interface device.
Using an interface device, a user can interact with an environment displayed by a computer system to perform functions and tasks on the computer, such as playing a game, experiencing a simulation or virtual reality environment, using a computer aided design system, operating a graphical user interface (GUI), or otherwise influencing events or images depicted on the screen. Common human-computer interface devices used for such interaction include a joystick, mouse, trackball, steering wheel, stylus, tablet, pressure-sensitive ball, or the like, that is connected to the computer system controlling the displayed environment.
In some interface devices, force feedback or tactile feedback is also provided to the user, also known more generally herein as xe2x80x9chaptic feedback.xe2x80x9d These types of interface devices can provide physical sensations which are felt by the user using the controller or manipulating the physical object of the interface device. One or more motors or other actuators are used in the device and are connect ed to the controlling computer system. The computer system controls forces on the haptic feedback device in conjunction and coordinated with displayed events and interactions on the host by sending control signals or commands to the haptic feedback device and the actuators.
Many low cost haptic feedback devices provide forces to the user by vibrating the manipulandum and/or the housing of the device that is held by the user. The output of simple vibration haptic feedback (tactile sensations) requires less complex hardware components and software control over the force-generating elements than does more sophisticated haptic feedback. For example, in many current game controllers for game consoles such as the Sony Playstation and the Nintendo 64, one or more motors are mounted in the housing of the controller and which are energized to provide the vibration forces. An eccentric mass is positioned on the shaft of each motor, and the shaft is rotated unidirectionally to cause the motor and the housing of the controller to vibrate. The host computer (console unit) provides commands to the controller to turn the vibration on or off or to increase or decrease the frequency of the vibration by varying the rate of rotation of the motor.
One problem with these currently-available implementations of vibration haptic feedback devices is that the vibrations that these implementations produce are very limited and cannot be significantly varied. For example, the frequency of the vibrations output by the controllers described above can be adjusted by the host computer, but the magnitude of these vibrations cannot be varied independently from the frequency. These devices can only provide vibration magnitudes that are directly proportional to frequency.
In addition, other prior art vibrotactile devices are limited in their ability to change the natural frequency of a moving mass in the actuator system, which is the frequency at which the magnitude of the output vibrations are the highest for a given power input. If the natural frequency can be varied, the resulting magnitude of vibrations can be greatly varied. The prior art devices thus severely limit the force feedback effects which can be experienced by a user of these devices.
The present invention is directed to controlling vibrotactile sensations in haptic feedback devices which are interfaced with a host application program. The present invention allows more varied and complex sensations to be provided using inexpensive electronics and mechanical parts.
More specifically, in one aspect of the present invention, a haptic feedback device for providing vibrotactile sensations to a user is coupled to a host computer. The haptic feedback device, such as a gamepad controller, mouse, remote control, etc., includes a housing grasped by the user, an actuator coupled to the housing, and a mass. The mass can be oscillated by the actuator and a coupling between the actuator and the mass or between the mass and the housing has a compliance that can be varied. Varying the compliance allows vibrotactile sensations having different magnitudes for a given drive signal to be output to the user grasping the housing.
Several different embodiments realize this aspect of the invention. In one embodiment, the compliance is contributed by a magnetic spring provided between the actuator and the mass, where the actuator includes a magnet and a coil, and where the mass is coupled to a pivoting member that includes at least one magnet that is moved by a magnetic field of the actuator. In another embodiment, the compliance is provided by a flexure coupling the mass to the housing, where the actuator is grounded to the housing and moves the mass which includes a magnet. A second grounded actuator can provide a magnetic force on the mass to provide a variable tension in the flexure. In other embodiments, the flexible member is a tapered member and is coupled to a rotary actuator that rotates the tapered member about its lengthwise axis to provide a variable compliance between the mass and housing. In other embodiments, the compliance is varied by moving a pair of grounded pincher rollers along a length of the flexible member.
In another aspect of the present invention, a haptic feedback device for providing vibrotactile sensations to a user is coupled to a host computer and includes a housing grasped by the user, a rotary actuator coupled to the housing, and an eccentric mass coupled to and rotatable by the actuator about an axis of rotation. The eccentric mass has an eccentricity that can be varied relative to the axis of rotation while the mass is rotating. Varying said eccentricity allows vibrotactile sensations having different magnitudes for a given drive signal to be output to the user grasping said housing.
Several different embodiments realize this aspect of the invention. In one embodiment, the eccentric mass includes a plurality of discs slidably coupled to a rotating shaft, where a magnetic field is controlled to cause a desired number of said discs to frictionally engage with said shaft to provide a desired eccentricity of the mass. In another embodiment, the mass includes a slotted member having a plurality of different slots radiating from a center aperture and having different lengths, where a rotated keyed portion engages in one of the slots to provide a desired eccentricity. In another embodiment, the mass includes a ring magnet coupled to a hub, where a magnetic field is provided to move the ring magnet relative to the axis of rotation and relative to the hub to vary the eccentricity. In another embodiment, the mass includes a hopper that encloses multiple balls, and where an inlet to the hopper can be opened to allow additional balls to move inside the hopper and change a center of mass of the hopper to change the eccentricity. In another embodiment, the mass includes a rotating disc having sockets, where at least one ball can be pulled into one of the sockets by a selective magnetic field, thereby changing a center of mass of the disc to change the eccentricity. In another embodiment, the mass includes an arm member coupled to a rotating shaft of the actuator, where a member is pivotably coupled to the arm such that a different eccentricity is provided when rotating the arm in one direction than when rotating the arm in the opposite direction.
The present invention advantageously provides a haptic feedback device that can output a wide variety of vibrotactile sensations. Both the frequency and amplitude of the vibrations can be controlled using bidirectional control features. Furthermore, a compliance between mass and ground and/or an eccentricity of the moving mass can be changed to change the natural frequency of oscillation of the mass, providing different vibration magnitudes for a given drive waveform. These features allow a much more efficient use of power for a desired vibration magnitude, a greater precision in the control of vibration sensations, and a wider range of sensations to be experienced by the user than in the prior art devices.
These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following specification of the invention and a study of the several figures of the drawing.